To inspect a printed substrate on which many electronic components are mounted, an X-ray inspection device using X-rays is known, as disclosed in Japanese Patent Application Laid-open No. 2003-315288 and Japanese Patent Application Laid-open No. 2002-189002. In such an X-ray inspection device, an inspection chamber is defined in a housing at which X-ray shielding processing has been performed to prevent exposure to X-rays, an X-ray source and an X-ray camera are installed in the inspection chamber, and X-rays are irradiated onto an inspection target (a printed substrate) and an X-ray image is captured using these devices. In order to carry a printed substrate into/out of the inspection chamber, a substrate table, to transfer the printed substrate on the substrate conveyor, is disposed in the housing.
Referring to FIG. 15, conveyor units 70P are disposed on a substrate table 60P, as disclosed in Japanese Patent Application Laid-open No. 2003-315288. The conveyor units 70P clamp a printed substrate W therebetween with respect to a substrate width direction (hereafter called “Y axis direction”) which is orthogonal to the carry in/out direction of the printed substrate W (hereafter called “X axis direction”). Since a dimension in the Y axis direction of the target printed substrate W for inspection varies respectively, a width adjustment unit for adjusting the space between the conveyor units 70P is disposed on the substrate table 60P of Japanese Patent Application Laid-open No. 2003-315288. The width adjustment unit is configured by a fixed frame 71P which secures the conveyor units 70P to a base 61P of the substrate table 60P, and a movable frame 72P which is movable in the Y axis direction from the fixed frame 71P. When clamping a printed substrate W between the fixed frame 71P and the movable frame 72P, the movable frame 72P moves in the Y axis direction so as to adjust the dimension in the Y axis direction.
As the high integration of printed substrates are promoted in recent years, the use of transmission imaging where X-rays diagonally irradiated onto an essential inspection area at an elevation angle with respect to a plane of the printed substrate (called “oblique view capturing” in the present description), in addition to transmission imaging where X-rays, are irradiated in a normal line direction of the printed circuit (called “direct view imaging” in the present description), is increasingly demanded when X-ray transmission inspection is performed on a printed substrate.
In the case of a configuration of Japanese Patent Application Laid-open No. 2003-315288, where a plurality of types of printed substrates W are clamped using the fixed frame 71P and the movable frame 72P, the space for an opening required for transmitting X-rays increases if X-ray inspection is executed using both the oblique view capturing and the direct view imaging, which could increase the size of the entire apparatus.
FIGS. 16A-16D are comparative diagrams depicting a cross-sectional view of an X-ray inspection device in which an X-ray source (not illustrated) is disposed above, and an X-ray camera is movably disposed below. FIG. 16A and FIG. 16B are diagrams according to the present invention, and FIG. 16C and FIG. 16D are diagrams according to the prior art. FIG. 16C and FIG. 16D show a state when a substrate table 60P of Japanese Patent Application Laid-open No. 2003-315288 shown in FIG. 15, for example, is used, and the substrate table 60P is supported on a frame 111P having an opening 120 to transmit X-rays between the X-ray source and the X-ray camera 50.
In order to perform the oblique view capturing using the fixed frame 71P in FIG. 16C and FIG. 16D, a space d2, to transmit X-rays, must be secured in advance as indicated by d2 in FIG. 16C, hence the fixed frame 71P is disposed at a position where the opening of the base 61P is always blocked. Therefore if the oblique view capturing is not required, the fixed frame 71P gets in the way and limits the width of a printed substrate W, which is required for direct view imaging.